In his first act as prime minister on Monday, Alexis Tsipras visited the war memorial in Kaisariani where 200 Greek resistance fighters were slaughtered by the Nazis in 1944.
The move did not go unnoticed in Berlin. Nor did Tsipras's decision hours later to receive the Russian ambassador before meeting any other foreign official.
Then came the announcement that radical academic Yanis Varoufakis, who once likened German austerity policies to "fiscal waterboarding", would be taking over as Greek finance minister. A short while later, Tsipras delivered another blow, criticizing an EU statement that warned Moscow of new sanctions.
The assumption in German Chancellor Angela Merkel's entourage before Sunday's Greek election was that Tsipras, the charismatic leader of the far-left Syriza party, would eke out a narrow victory, struggle to form a coalition, and if he managed to do so, shift quickly from confrontation to compromise mode.
Instead, after cruising to victory and clinching a fast-track coalition deal with the right-wing Independent Greeks party, he has signaled in his first days in office that he has no intention of backing down, unsettling officials in Berlin, some of whom admit to shock at the 40-year-old's fiery start.
"No doubt about it, we were surprised by the size of the Syriza victory and the speed with which Tsipras clinched a coalition," said one senior German official, who requested anonymity because of the sensitivity of the issue.
Another said Tsipras's choice of coalition partner and finance minister were "not good signs", while a third admitted to being "stunned" by the Greek leader's first days in office.